Yes, if the aging effect concerns the pitch machine, it might be similar to
the drug effect. There is at least one other medical drug that has the same
effect. Based on a specific characteristic that the two drugs have in common
we could suggest a possible neurochemical effect on the pitch extracting
mechanism.

However, the big difference between aging and taking Tegretol is that
musicians have great problems in adapting to the drug effect. This was how
the case study started. The pianist was happy with the intended effect of
the drug and wanted to go on taking it. But the interference of the pitch
shift with her work at the piano was so annoying that she asked if the
problem could be examined and possibly resolved. In the end it could not be
resolved. As opposed to aging, the level of the chemical in the blood is not
constant over a long time. This makes it impossible for some musicians to
adapt fast enough to the pitch shifts.

It has indeed tended to go down for me, though not reliably so. The strange
thing is that I still have this feeling of certainty when I name notes, even
when I'm a semitone off. This makes me think that the effect is peripheral
in origin, and that the central auditory system still interprets the
information it receives correctly. There's a related phenomenon that occurs
when people take carbamazepine (Tegretol). Those with absolute pitch hear a
downward pitch shift that they generally describe as around a semitone. Its
extent appears to increase with increasing frequency in an orderly fashion
over a six octave range. Braun and Chaloupa (Hearing Research, 2005, 210,
85-92) were able to plot this in a concert pianist with absolute pitch who
made judgments both under carbamazepine and under placebo.

Several older persons who have had absolute pitch in their young years
experience perceiving a pitch by at least a half-tone (minor second)
higher than what it actually is ? a phenomenon that the French calls the
"climb of the tuning fork" ("montee du diapason"). Since I am one of
those unfortunate individuals, I have been wondering what its
physiological explanation is. Can anyone on the list offer one?